JP2007077858A - Exhaust configuration for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust configuration for a vehicle, reducing restriction of arrangement or the like while making variable an exhaust gas merge length which is the length to a point where exhaust gas from different banks merge. <P>SOLUTION: The exhaust configuration 10 for the vehicle includes a right bank exhaust pipe 22 and a left bank exhaust pipe 24 independently communicated to exhaust parts of a left and a right bank 14, 16 of the internal combustion engine 12. Rear side opening ends 22A, 22B of the left bank exhaust pipe 24 and the right bank exhaust pipe 22 are set at a second merging part making exhaust gas merged at a position of distance L1 from an exhaust part of the engine 12, and is provided in a second expansion chamber of a muffler 26. Through holes 22B, 24B as a first merge part making exhaust gas merged at distance L2 from the exhaust parts of the left bank exhaust pipe 24 and the right bank exhaust pipe 22 is provided in a first expansion chamber 32 of the muffler 26. The through holes 22B, 24B are opened and closed by open close valves 42, 44. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust structure for a vehicle for exhausting exhaust gas from an internal combustion engine having a pair of banks.

In order to improve the output at each rotation speed of the internal combustion engine, a plurality of communication pipes that connect the exhaust pipes of each bank and a valve that opens and closes each communication pipe are provided, and the valves are opened and closed according to the engine speed. Thus, a technique is known in which the exhaust merging length (so-called dual length) until the exhaust gas merges from the exhaust part of the engine is variable (see, for example, Patent Document 1).
Japanese Utility Model Publication No. 4-093722 JP 2004-204802 A JP 2003-206737 A JP-A-5-106449

  However, in the conventional technology as described above, it is necessary to provide a communication pipe that communicates a pair of exhaust pipes, and there are restrictions on the arrangement and structure of the exhaust system.

  In view of the above-described facts, an object of the present invention is to provide a vehicle exhaust structure in which the exhaust merge length, which is the length until exhaust of different banks merges, is variable, and restrictions on the arrangement and the like are reduced. .

  In order to achieve the above object, an exhaust structure for a vehicle according to a first aspect of the present invention communicates with an exhaust portion of a first bank in an internal combustion engine, and a length from the exhaust portion becomes a first predetermined length. A first exhaust pipe having a first opening provided at a position and a second opening provided at a position where a length from the exhaust portion is a second predetermined length longer than the first predetermined length A first opening provided at a position where the length from the exhaust portion is a first predetermined length, and a length from the exhaust portion. A second exhaust pipe having a second opening provided at a position having a second predetermined length longer than the first predetermined length; and a first space and a second space partitioned by a separator. And the first exhaust pipe and the second exhaust pipe are respectively introduced, The first opening of the first exhaust pipe and the first opening of the second exhaust pipe are disposed in the first space, and the second opening of the first exhaust pipe and the first opening The second opening of the second exhaust pipe is disposed in the second space, the muffler is disposed in the first space, the first opening of the first exhaust pipe, and the second exhaust pipe. And an opening / closing means capable of opening and closing the first opening of the two exhaust pipes in synchronization.

  In the exhaust structure for a vehicle according to claim 1, the opening and closing means opens the first openings of the first and second exhaust pipes for the exhaust of the first and second exhaust pipes communicating with different banks of the engine. In the state in which the first opening is merged from the exhaust part of each bank at the position of the first predetermined length, the opening / closing means closes the first openings of the first and second exhaust pipes. First, the gas flows from the exhaust part of each bank at a position having a second predetermined length longer than the first predetermined length. As a result, for example, the length from the exhaust part of each bank to the merge (hereinafter referred to as the exhaust merge length) can be switched between the first predetermined length and the second predetermined length in accordance with the engine speed. By this switching, at the timing when both the intake and exhaust valves of the engine are open, the reflected negative pressure wave of the own cylinder is synchronized to increase the intake amount, and the wraparound blowdown wave (positive pressure wave) of the previous cylinder or the next cylinder is synchronized ( It is possible to improve the output (torque) at each rotational speed of the engine.

  Here, in the vehicle exhaust structure, the first openings of the first and second exhaust pipes are disposed in the first space of the muffler, and the second of the first and second exhaust pipes are respectively provided. Is arranged in the second space of the muffler. In other words, since the variable structure of the exhaust merging length is disposed in the muffler, the communication for merging the first and second exhaust pipes is performed. There is no need to provide a tube. For this reason, the restrictions accompanying installation of the communication pipe are eliminated.

  In addition, since the exhaust from the first and second exhaust pipes merge while expanding in multiple directions in the space of the muffler having a larger cross section than the first and second exhaust pipes, a large reflected negative pressure wave is generated. can get. In addition, since the exhaust gas from the first and second exhaust pipes merges in the muffler space, the blow-down wave is less likely to enter the cylinder that has both the intake and exhaust valves open. As a result, the effect of improving the engine output by switching the exhaust merging length is increased.

  Thus, in the vehicle exhaust structure according to the first aspect, restrictions on the arrangement and the like are reduced while the exhaust merge length, which is the length until exhaust of different banks merges, is variable.

  A vehicle exhaust structure according to a second aspect of the present invention is the vehicle exhaust structure according to the first aspect, wherein the opening and closing means includes a first valve body that opens and closes the first opening of the first exhaust pipe. The second valve body that opens and closes the first opening of the second exhaust pipe is opened and closed in synchronization with the first opening of the first exhaust pipe and the first opening of the second exhaust pipe. It is the on-off valve apparatus comprised by connecting so.

  In the vehicle exhaust structure according to claim 2, the on-off valve device having the first valve body and the second valve body connected to each other opens and closes the first openings of the first and second exhaust pipes. Since this on-off valve device opens and closes each first opening in one operation (with one power source), the structure is simple.

  According to a third aspect of the present invention, there is provided an exhaust structure for a vehicle having two exhaust passages independently communicated with exhaust portions of different banks of an internal combustion engine, and exhausting the two exhaust passages from the respective exhaust portions. An exhaust structure for a vehicle that can switch an exhaust merge length to a portion where the exhaust merge occurs to a different length, wherein the exhaust of the two exhaust paths can be merged at a position where the exhaust merge length becomes a predetermined length. A first merging portion, a second merging portion for merging the exhaust of the two exhaust passages at a position where the exhaust merging length is longer than that when merging at the first merging portion, and the two exhausts An exhaust merging length switching means for selectively switching between a state where the exhaust of the passage merges at the first merging portion and a state where the exhaust does not merge, and one of the first merging portion and the second merging portion is inside Arranged in the space formed by the first merging portion and So that the exhaust of the two exhaust passages in one of the two merging section are joined through the space, and a, a muffler, wherein the two exhaust path is introduced.

  The exhaust structure for a vehicle according to claim 3, wherein the exhaust of the two exhaust passages communicating with different banks of the engine has the first merging when the exhaust merging length switching means takes a merging state at the first merging portion. When the exhaust gas merging length switching means takes a non-merging state at the first merging portion, the second merging portion, that is, the exhaust gas of each bank. The first merge occurs at a position that is longer than a predetermined length from the part. Thereby, the exhaust merge length until it merges from the exhaust part of each bank according to the rotation speed of an engine, for example can be switched to a different length. By this switching, at the timing when both the intake and exhaust valves of the engine are opened, the reflected negative pressure wave of the own cylinder is synchronized to increase the intake amount, and the wraparound blowdown wave (positive pressure wave) of the previous cylinder or the next cylinder is synchronized ( (Increase in intake / exhaust resistance due to the engine) can be prevented, and the output (torque) at each rotational speed of the engine can be improved.

  Here, in this vehicle exhaust structure, since either one of the first merging portion and the second merging portion is arranged in the space of the muffler, the gas in the two exhaust passages is first merged with either one of the first merging portion and the second merging portion. In this case, the exhaust gas merges while expanding in multiple directions within the space of the muffler having a larger cross section than the first and second exhaust pipes, and thus a large reflected negative pressure wave is obtained. Further, since the exhaust gas from the first and second exhaust pipes merges in the space of the muffler, it becomes difficult for the blowdown wave to go around to the cylinder in which both the intake and exhaust valves are open. As a result, the effect of improving the engine output is increased in the switching state of at least one of the exhaust merging lengths.

  Moreover, it is not necessary to provide a communication pipe for merging the two exhaust passages at the merging portion arranged in the muffler space among the first and second merging portions. For this reason, the restrictions accompanying installation of the communication pipe are eliminated. Even if this communication pipe is provided, the communication pipe is arranged in the space of the muffler, so that there are few restrictions on the arrangement of the communication pipe. Further, even if the length of the muffler is short, if one of the merging portions is arranged outside the muffler, the difference in the exhaust merging length due to switching can be set large.

  A vehicle exhaust structure according to a fourth aspect of the present invention is the vehicle exhaust structure according to the third aspect, wherein the muffler has another space partitioned from the space, and the first merging portion and The other of the second merging portions is disposed in another space of the muffler.

  In the vehicle exhaust structure according to the fourth aspect, the first merging portion and the second merging portion are arranged in different spaces partitioned from each other. As a result, restrictions associated with the installation of the communication pipe, or restrictions on the arrangement of the communication pipe and the like are further reduced.

  A vehicle exhaust structure according to a fifth aspect of the present invention is the vehicle exhaust structure according to the fourth aspect, wherein the other of the first merging portion and the second merging portion is the gas through the other space of the muffler. Are arranged in the other space so as to merge.

  In the exhaust structure for a vehicle according to claim 5, the first merging portion and the second merging portion merge the exhaust of the two exhaust passages through a space in which the first merging portion and the second merging portion are respectively arranged in different spaces. Let For this reason, in any switching state of the exhaust merging length, the exhaust gas is merged while being expanded, so that the engine output improvement effect is increased.

  The exhaust structure for a vehicle according to a sixth aspect of the invention is the exhaust structure for a vehicle according to the third or fourth aspect, wherein the two exhaust passages are internally separated by a partition wall provided along the exhaust flow direction. The partition wall includes a divided pipe, and the first junction is provided in the partition wall.

  In the exhaust structure for a vehicle according to the sixth aspect, since a split pipe in which the inside of one pipe (pipe wall) is partitioned by a partition wall is used, the installation space of the exhaust path (the entire exhaust structure) can be reduced. In addition, since the first merging portion is provided in the partition wall, the exhaust merging and non-merging in the first merging portion can be switched by one opening / closing means (valve element or the like). Furthermore, the split pipe has a small surface area and a small heat capacity compared to a configuration using two independent exhaust pipes, so that the exhaust temperature rises in a short time after the engine is started, and the output (torque) is improved. Time until it is obtained is shortened.

  A vehicle exhaust structure according to a seventh aspect of the present invention is the vehicle exhaust structure according to any one of the third to sixth aspects, wherein the two exhaust passages are provided along a flow direction of the exhaust gas. Including a portion constituted by a dividing pipe whose interior is partitioned by a partition wall, and an end of the dividing pipe is used as the second merging portion, and on both sides in the circumferential direction with respect to the partition wall in the pipe wall of the dividing pipe The provided tube wall penetrating portion is the first merging portion, and at least the first merging portion is disposed in the space of the muffler.

  In the exhaust structure for a vehicle according to the seventh aspect, since a split pipe in which the inside of one pipe (tube wall) is partitioned by a partition wall is used, the installation space of the exhaust path (the entire exhaust structure) can be reduced. Since the first merging portion of the two exhaust passages is a tube wall penetrating portion that penetrates the tube wall of the dividing pipe on both sides of the partition wall, the gas merging through the muffler space is performed using the dividing pipe. Can do. On the other hand, since the end of the split pipe is the second joining portion, the second joining portion is installed without providing a communication tube even if it is configured outside the space.

  Furthermore, the split pipe has a small surface area and a small heat capacity compared to a configuration using two independent exhaust pipes, so that the exhaust temperature rises in a short time after the engine is started, and the output (torque) is improved. Time until it is obtained is shortened.

  An exhaust structure for a vehicle according to an eighth aspect of the present invention is the exhaust structure for a vehicle according to any one of the third to seventh aspects, wherein the first merging portion is disposed in the space of the muffler. The exhaust merging length switching means is configured to switch between merging and non-merging of the exhaust of the two exhaust passages in the first merging portion, and the two of the two exhaust passages. Switching between communication and non-communication with respect to the space in the muffler is performed by one valve body.

  In the exhaust structure for a vehicle according to claim 8, the on-off valve device is configured to switch between merging / non-merging of exhaust between two exhausts in the first merging portion, and between the first merging portion of the two exhaust pipes and the space. Since switching between communication and non-communication is performed by the operation of one valve body (with one power source), the structure is simple.

  An exhaust structure for a vehicle according to a ninth aspect of the present invention has two exhaust passages independently communicated with exhaust portions of different banks of the internal combustion engine, and exhausts of the two exhaust passages from the respective exhaust portions. An exhaust structure for a vehicle that can switch an exhaust merge length up to a portion where the two are merged to different lengths, wherein the two exhaust paths are divided by a partition provided along an exhaust flow direction. A portion constituted by a pipe, a first merging portion provided on a partition wall in the dividing pipe and opened and closed by an opening / closing means, and disposed downstream of the first merging portion in the dividing pipe in the gas flow direction. And a second merging portion.

  In the vehicle exhaust structure according to the ninth aspect, the two exhaust passages communicating with different banks of the engine are configured by using divided pipes in which one pipe (tube wall) is partitioned by a partition wall. For this reason, the installation space of the exhaust path (the whole exhaust structure) can be reduced. Moreover, the 1st junction part provided in the partition can be set, without providing a communicating pipe. On the other hand, a 2nd junction part can be set without providing a communicating pipe by providing in a partition downstream from a 1st junction part, or making it the terminal of a division pipe (partition wall). As described above, in the vehicle exhaust structure according to the ninth aspect, restrictions on the arrangement and the like are reduced while the exhaust merge length, which is the length until exhaust of different banks merges, is variable.

  Furthermore, the split pipe has a small surface area and a small heat capacity compared to a configuration using two independent exhaust pipes, so that the exhaust temperature rises in a short time after the engine is started, and the output (torque) is improved. Time until it is obtained is shortened.

  A vehicle exhaust structure according to a tenth aspect of the present invention is the vehicle exhaust structure according to any one of the first to ninth aspects, wherein the first merging portion or the first opening of each of the exhaust pipes is used. Further, a cooling means for lowering the temperature of the exhaust was provided upstream.

  In the exhaust structure for a vehicle according to claim 10, the exhaust gas in the first and second exhaust pipes or the two exhaust passages is cooled by the cooling means before joining, and the exhaust temperature is reduced. For this reason, the propagation speed of the blowdown wave is reduced, and the output (torque) improvement effect is increased as compared with the case where the exhaust temperature is high.

  The vehicle exhaust structure according to an eleventh aspect of the present invention is the vehicle exhaust structure according to the tenth aspect, wherein the cooling means includes the two exhaust passages that communicate independently with different banks of the internal combustion engine. A bracket having a gas cooling section that spans the first and second exhaust pipes and crosses the exhaust path or the exhaust pipe, and a cooled part that is positioned outside the exhaust path or the exhaust pipe.

  12. The exhaust structure for a vehicle according to claim 11, wherein a portion of the bracket that crosses and connects mutually independent exhaust passages or exhaust pipes cools the exhaust by heat exchange with the exhaust, and the exhaust in the bracket. A portion located outside the passage or the exhaust pipe is a cooled portion that is cooled by contact with external air. For this reason, the structure is simple.

  An exhaust structure for a vehicle according to a twelfth aspect of the invention is the exhaust structure for a vehicle according to any one of the first to eleventh aspects, and a rotational speed detection means for detecting the rotational speed of the internal combustion engine. Based on exhaust temperature detection means for detecting the temperature of the exhaust, actuator for operating the exhaust merging length switching means or the opening / closing means, detection results of the rotation speed detection means, and detection results of the exhaust temperature detection means And a control device for operating the actuator.

  In the exhaust structure for a vehicle according to claim 12, the control device appropriately operates the actuator based on the engine speed that is the detection result of the speed detection means and the exhaust temperature that is the detection result of the exhaust temperature detection means. The presence / absence of merging of one merging portion or the opening / closing of the first opening, that is, the exhaust merging length is switched. For this reason, for example, compared with the configuration in which the exhaust merge length is switched based only on the engine speed, the exhaust merge length can be switched at an appropriate timing considering the propagation speed of exhaust pulsation (blowdown wave or the like). The engine output can be effectively improved.

  An exhaust structure for a vehicle according to a thirteenth aspect of the present invention has two exhaust passages that are independently communicated with exhaust portions of different banks of the internal combustion engine, and the exhaust portions of the two exhaust passages are communicated from the exhaust portions. An exhaust structure for a vehicle that can switch an exhaust gas merge length to a portion where the gas flows merge to a different length, the exhaust gas merge length switching means for switching the exhaust gas merge length to a different length, and rotation of the internal combustion engine A rotation number detection means for detecting the number of exhaust gases, an exhaust gas temperature detection means for detecting the temperature of the exhaust gas, a detection result of the rotation speed detection means, and a detection result of the exhaust gas temperature detection means, And a control device for operating the means.

  In the exhaust structure for a vehicle according to claim 13, the control device changes the exhaust merging length switching means based on the engine speed that is the detection result of the speed detection means and the exhaust temperature that is the detection result of the exhaust temperature detection means. The exhaust merge length is switched by operating appropriately. For this reason, for example, compared with the configuration in which the exhaust merge length is switched based only on the engine speed, the exhaust merge length can be switched at an appropriate timing considering the propagation speed of exhaust pulsation (blowdown wave or the like). The engine output can be effectively improved.

  As described above, the exhaust structure for a vehicle according to the present invention has an excellent effect that the restriction on the arrangement and the like is reduced while the exhaust merge length, which is the length until exhaust of different banks merges, is variable.

[First embodiment]
A vehicle exhaust structure 10 as a vehicle exhaust structure according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 6. First, the mechanical configuration of the vehicle exhaust structure 10 will be described, then the control of the vehicle exhaust structure 10 will be described, and then the effects of the vehicle exhaust structure 10 will be described. For convenience of explanation, a direction indicated by an arrow FR appropriately shown in each drawing is a forward direction (traveling direction) of an automobile to which the vehicle exhaust structure 10 is applied.

  (Mechanical structure)

  FIG. 1 is a plan view schematically showing a vehicle exhaust structure 10 partially cut away. As shown in this figure, the vehicle exhaust structure 10 is a structure for discharging exhaust gas, which is combustion exhaust gas of the internal combustion engine 12, to the outside of the vehicle. The internal combustion engine 12 is a V-type or horizontally opposed engine having a right bank 14 as a first bank and a left bank 16 as a second bank. In this embodiment, the banks 14 and 16 are The engine is a 6-cylinder engine having 3 cylinders (cylinders).

  Further, as shown in FIG. 4, the internal combustion engine 12 includes a first cylinder 14A in the right bank 14, a second cylinder 16A in the left bank 16, a third cylinder 14B in the right bank 14, and a fourth cylinder 16B in the left bank 16. The explosion process is performed in the order of the fifth cylinder 14C in the right bank 14, the sixth cylinder 16C in the left bank 16, the first cylinder 14A in the right bank 14, and so on.

  As shown in FIG. 1, a right exhaust manifold 18 is connected to the right bank 14 of the engine 12. Specifically, the right exhaust manifold 18 has one end connected to the exhaust port of each cylinder 14A, 14B, 14C of the right bank 14 independently, and the other end of the branch pipes 18A, 18B, 18C to the junction 18D. And merged. Each branch pipe 18A, 18B, 18C is configured such that the length from the connected exhaust port to the merging portion 18D is substantially equal.

  Similarly, a left exhaust manifold 20 is connected to the left bank 16 of the engine 12. Specifically, the left exhaust manifold 20 has one end connected to the exhaust port of each cylinder 16A, 16B, 16C of the left bank 16 independently, and the other end of the branch pipes 20A, 20B, 20C to the junction 20D. And merged. Each of the branch pipes 20A, 20B, and 20C has substantially the same length from the connected exhaust port to the merge portion 20D, and the length from each exhaust port of the right bank 14 to the merge portion 18D. It is comprised so that it may become.

  Then, one end (front end) of a right bank exhaust pipe 22 serving as a first exhaust pipe is connected to the merging portion 18D of the right exhaust manifold 18. One end of a left bank exhaust pipe 24 as a second exhaust pipe is connected to the merging portion 20D of the left exhaust manifold 20. The other ends (rear ends) of the right bank exhaust pipe 22 and the left bank exhaust pipe 24 are introduced into the muffler 26. A catalytic converter may be provided in the middle of the right bank exhaust pipe 22 and the left bank exhaust pipe 24, respectively.

  The muffler 26 is configured such that the front and rear opening ends of a muffler cylinder 26A having a substantially elliptical frame cross section are closed by a front plate 26B and a rear plate 26C, respectively, and a sealed space is formed inside. In the muffler 26, a pair of separators 28 and 30 are fixedly disposed substantially in parallel with the front plate 26B and the rear plate 26C, respectively.

  Thereby, in the muffler 26, a first space 32 is formed between the front plate 26B and the front separator 28, and a second space 34 is formed between the rear plate 26C and the rear separator 30. A third space 36 is formed between the pair of separators 28 and 30.

  In the muffler 26, the other end side of the right bank exhaust pipe 22 and the left bank exhaust pipe 24 is introduced through the front plate 26B and the front and rear separators 28 and 30 in an airtight state. The second opening in the right bank exhaust pipe 22 and the left bank exhaust pipe 24 and the opening ends 22A and 24A as the second merging portion are opened in the second space 34 in the muffler 26, respectively.

  From the exhaust ports of the cylinders 14A, 14B, 14C, 16A, 16B, and 16C of the right bank 14 and the left bank 16, open ends 22A and 24A in the second space 34 of the right bank exhaust pipe 22 and the left bank exhaust pipe 24, respectively. The lengths up to are set as equal lengths L1. The right bank 14 and the left bank 16 may have different lengths L1 (dual length described later). Also in this configuration, an effective output improvement effect described later can be obtained by, for example, a control device.

  Further, a front portion of an exhaust main pipe 38 whose rear end is opened so that exhaust gas can be discharged outside the vehicle is introduced into the muffler 26. The front part of the exhaust main pipe 38 penetrates the front plate 26B and the front and rear separators 28 and 30 in the muffler 26 in an airtight state, and the front opening end 38A is opened in the first space 32. Further, a communication pipe 40 is provided in the muffler 26 so as to penetrate the front and rear separators 28 and 30 in an airtight state and communicate the first space 32 and the second space 34.

  As a result, in the vehicle exhaust structure 10, the 12 exhaust gases flowing through the right bank exhaust pipe 22 and the left bank exhaust pipe 24 enter the second space 34 in the muffler 26 where the length from the exhaust port is L1. And then flows into the exhaust main pipe 38 through the communication pipe 40 and the first space 32 and is discharged outside the vehicle.

  In the vehicle exhaust structure 10, exhaust until the exhaust of the right exhaust manifold 18 and the left exhaust manifold 20 first merges from the exhaust port of each bank 14, 16, that is, the connection portion of the right exhaust manifold 18 and the left exhaust manifold 20. The joining length (hereinafter referred to as “dual length”) can be switched between the length L1 described above and the distance L2 shorter than the length L1.

  Specifically, the right bank exhaust pipe 22 and the left bank exhaust pipe 24 are respectively provided with a first opening and through holes 22B and 24B as a first junction. Each through hole 22B, 24B is provided at a position where the length from the exhaust port of the corresponding bank 14, 16 is L2, and opens in the first space 32 in the muffler 26, respectively.

  The lengths of the right bank exhaust pipe 22 and the left bank exhaust pipe 24 from the through holes 22B and 24B to the opening ends 22A and 24A are respectively set to length L3, and L1 = L2 + L3. In this embodiment, the dual length L1 is set to about 2 m, the dual length L2 is set to about 1 m, and the dual length difference L3 is set to about 1 m.

  Further, the vehicle exhaust structure 10 includes opening / closing means for opening / closing the through holes 22B, 24B and opening / closing valves 42, 44 as exhaust merging length difference switching means. Thus, in the vehicle exhaust structure 10, when the open / close valves 42 and 44 close the through holes 22B and 24B, the exhaust gas of the right bank exhaust pipe 22 and the left bank exhaust pipe 24 is opened at the opening ends 22A and 24A. In the state where the second space 34 is joined, that is, in the state of the dual length L1 and the open / close valves 42 and 44 open the through holes 22B and 24B, the right bank exhaust pipe 22 and the left bank exhaust pipe 24 The exhaust gas is merged in the first space 32 in which the through holes 22B and 24B are opened, that is, the dual length L2.

  In this embodiment, the first space 32 in which the through holes 22 </ b> B and 24 </ b> B in the muffler 26 are disposed is an expansion that expands the exhaust gas introduced from the right bank exhaust pipe 22, the left bank exhaust pipe 24, or the communication pipe 40. Functions as a chamber. Further, the second space 34 in which the opening ends 22A and 24A of the muffler 26 are disposed functions as an expansion chamber for expanding the exhaust gas introduced from the right bank exhaust pipe 22 and the left bank exhaust pipe 24. In the following description, the first space 32 may be referred to as a first expansion chamber 32, and the second space 34 may be referred to as a second expansion chamber 34.

  As shown in FIG. 1, each open / close valve 42, 44 is disposed in the first expansion chamber 32 to drive the valve body 46, and a valve body 46 that can take an open position and a closed position of the through holes 22 </ b> B, 24 </ b> B. And an actuator 48 for moving to an open position or a closed position. The actuator 48 is disposed outside the muffler 26.

  As shown in FIGS. 2 and 3, the valve body 46 extends along the outer peripheral surface of the right bank exhaust pipe 22 and the left bank exhaust pipe 24 when viewed from the axial direction in the right bank exhaust pipe 22 and the left bank exhaust pipe 24. It is formed in an arc shape. The valve body 46 is rotatable through a support shaft 50 to a shaft support portion 49 fixed to the right bank exhaust pipe 22 and the left bank exhaust pipe 24 in bearing portions 46A provided at respective circumferential ends. It is supported by. The valve body 46 is configured to be able to take a closed position shown in FIG. 3 (A) and an open position shown in FIG. 3 (B) by turning around the support shaft 50.

  As shown in FIG. 2, the support shaft 50 passes through the front plate 26 </ b> B and the front end side protrudes outside the muffler 26. A pulley 52 constituting the actuator 48 is fixed to the tip of the support shaft 50 so as to rotate coaxially and integrally. The pulley 52, that is, the support shaft 50 is urged by the return spring 54 toward the closing position where the valve body 46 is in close contact with the outer peripheral surfaces of the right bank exhaust pipe 22 and the left bank exhaust pipe 24. The return spring 54 is a torsion coil spring. One end of the return spring 54 is locked to the spring receiving portion 52A of the pulley 52, and the other end is locked to a bracket 56 fixed to the front plate 26B.

  Further, one end of a cable 58 is wound around the pulley 52. By pulling this cable 58 in the direction of arrow A shown in FIG. It is designed to rotate around. As shown in FIG. 1, the other end of the cable 58 is connected to a winding device 60 (or a wire pulling device). The winding device 60 winds up the cable 58 when an internal motor (not shown) operates. It is set as the structure pulled in A direction. The intake negative pressure of the engine 12 may be used as the driving force of the winding device 60.

  Thus, the opening / closing valves 42 and 44 hold the valve body 46 in the closed position by the urging force of the return spring 54 when the winding device 60 is not in operation, and the valve body 46 is brought into the open position by the operation of the winding device 60. It is configured to move. And the winding device 60 of each on-off valve 42 and 44 is electrically connected to engine ECU62 which is a control apparatus.

  The engine ECU 62 is electrically connected to a rotation detector 64 that outputs a signal corresponding to the rotational speed of the engine 12, and the winding device 60 of the on-off valves 42 and 44 is based on the signal from the rotation detector 64. The operation is controlled. In this embodiment, the engine ECU 62 controls each winding device 60 synchronously so that the open / close states of the through holes 22B and 24B by the valve bodies 46 of the open / close valves 42 and 44 are the same.

  (Control by engine ECU)

  First, the operation of the engine 12 which is a V-type or horizontally opposed type six-cylinder four-cycle engine will be described. FIG. 5 shows a cycle of the first cylinder 14A, the second cylinder 16A, and the third cylinder 14B shown in FIG. 4 in a timing (cycle) chart. From this figure, the first cylinder 14A, the second cylinder 16A, and the third cylinder 14B repeat the steps of combustion (explosion), exhaust, intake, compression, combustion,... While shifting the phase by 120 degrees.

  When shifting from the exhaust process to the intake process, a so-called valve overlap timing occurs in each cylinder of the engine 12 during a period in which both the intake port (intake valve) and the exhaust port (exhaust valve) are opened. This valve overlap timing Tvo is shown in the chart of the second cylinder 16A in FIG.

  By the way, the blowdown wave Wb1 generated by the exhaust gas generated in the first cylinder 14A belonging to a different bank which is the front cylinder with respect to the second cylinder 16A is synchronized with the valve overlap timing Tvo of the second cylinder 16A which is the own cylinder. Then, as shown in FIG. 4, the second cylinder 16A wraps around as a positive pressure wave. That is, when the blowdown wave Wb1 reaches the merge point of the exhaust gas in the banks 14 and 16 at the valve overlap timing Tvo of the second cylinder 16A, the blowdown wave Wb1 wraps around the second cylinder 16A as a positive pressure wave.

  Similarly, the blowdown wave Wb3 that is generated in the third cylinder 14B that is the next cylinder to the second cylinder 16A and belongs to a different bank and propagates by the exhaust gas is generated at the valve overlap timing Tvo of the second cylinder 16A that is the own cylinder. When synchronized, the air enters the second cylinder 16A as a positive pressure wave as shown in FIG. That is, when the blowdown wave Wb3 reaches the merge point of the exhaust gas in each bank 14 and 16 at the valve overlap timing Tvo of the second cylinder 16A, the blowdown wave Wb3 wraps around the second cylinder 16A as a positive pressure wave.

  When these blow-down waves Wb1 and Wb3, which are positive pressure waves, enter the second cylinder 16A, intake resistance is reduced and the amount of intake air to the second cylinder 16A is reduced, causing the output torque of the engine 12 to be reduced.

  On the other hand, when the blowdown wave of the own cylinder reaches the merge point of the exhaust gas of each bank 14 and 16 and is reflected as shown in FIG. 4, it becomes a negative pressure wave, so this reflected negative pressure wave Wr is used as the valve overlap timing of the own cylinder. In synchronization with Tvo, the intake resistance decreases and the intake amount increases, contributing to an increase in the output torque of the engine 12.

  Here, in the internal combustion engine 12 for automobiles, the engine speed changes according to the running state of the automobile. Therefore, when the dual length from the exhaust port to the exhaust gas merging point of each bank 14 and 16 is constant, the blow-down wave and reflection negative wave synchronized with the valve overlap timing Tvo of the own cylinder according to the engine speed. The pressure wave changes (including the case where none of them are synchronized). Generally, when the dual length is long, the valve overlap timing Tvo of the own cylinder 16A and the blowdown wave Wb1 of the front cylinder 14A are easily synchronized when the rotational speed of the engine 12 is high, and when the dual length is short, the rotation of the engine 12 When the number is low, the valve overlap timing Tvo of the own cylinder 16A and the blowdown wave Wb3 of the next cylinder 14B are easily synchronized.

  The diagram shown in FIG. 6 is a diagram showing the relationship between the rotational speed of the engine 12 and the output torque, and the case where the dual length is L1 is indicated by a two-dot chain line, and the dual length is L2 (<L1). Is shown by a broken line. From this figure, at a predetermined rotation speed N0 where two diagrams intersect, the output torque is larger when the dual length is L1 (long) on the low rotation side, and the dual length is L2 (short) on the high rotation side. ) Shows that the output torque increases.

  Based on the above knowledge, when the engine ECU 62 constituting the vehicle exhaust structure 10 according to the present embodiment determines that the rotational speed of the engine 12 is equal to or less than the set rotational speed N0 based on the output of the rotation detector 64 Further, the winding device 60 of each open / close valve 42, 44 is deactivated to maintain the closed state of the through holes 22B, 24B, and the dual length is set to L1. On the other hand, when the engine ECU 62 determines that the rotational speed of the engine 12 exceeds the set rotational speed N0 based on the output of the rotation detector 64, the engine ECU 62 operates the winding devices 60 of the on-off valves 42 and 44 to pass through holes. 22B and 24B are opened, and the dual length is set to L2.

  The set rotational speed N0 varies depending on the number of engine cylinders, intake / exhaust valve timing, and the like.

  (Function and Effect) Next, the function of this embodiment will be described.

  In the vehicle exhaust structure 10 having the above-described configuration, the exhaust gas in the right bank 14 of the engine 12 is discharged outside the vehicle via the right exhaust manifold 18, the right bank exhaust pipe 22, and the muffler 26, and the exhaust gas in the left bank 16 is discharged. The exhaust gas is discharged out of the vehicle through the left bank exhaust pipe 24, the left exhaust manifold 20, and the muffler 26.

  Here, in the vehicle exhaust structure 10, the length until the exhaust gases of the banks 14 and 16 first merge can be switched between the dual length L1 and the dual length L2, and the engine speed is set to the set speed. When the engine speed is N0 or less, the dual length L1 is selected, and when the engine speed exceeds the set speed N0, the dual length L2 is switched.

  Therefore, when the engine speed is high, the blowdown wave Wb1 of the previous cylinder is synchronized with the valve overlap timing Tvo of the own cylinder, and when the engine speed is low, the blowdown wave Wb3 of the next cylinder is Both synchronization with the valve overlap timing Tvo is prevented or significantly suppressed. Further, the reflected negative pressure wave of the own cylinder is easily synchronized with the valve overlap timing Tvo of the own cylinder.

  As described above, in the automobile to which the vehicle exhaust structure 10 is applied, the output torque and output of the engine 12 are improved in a wide rotation speed region (almost the entire region).

  Further, since the exhaust gases of the banks 14 and 16 first merge in the first expansion chamber 32 or the second expansion chamber 34 of the muffler 26, in other words, the exhaust gas is multidirectional in the expansion chamber having a large cross-sectional area. Therefore, the inverted negative pressure wave obtained becomes large. Thereby, further torque improvement is expected by the former. Further, by combining the exhaust gases of the banks 14 and 16 in the expansion chambers 32 and 34, the blow-down waves of the front cylinder and the next cylinder are exhausted from the banks on the opposite side through the relatively small through holes 22B and 24B. It is hard to get around. As a result, even when the blowdown of the front cylinder and the next cylinder is synchronized with the valve overlap timing Tvo (rotation speed), the torque drop is reduced. Therefore, by combining the exhaust gases of the banks 14 and 16 through the expansion chambers 32 and 34 in the muffler 26, the engine exhaust structure 10 has a large engine output improvement effect.

  Furthermore, in the vehicle exhaust structure 10, the through holes 22 </ b> B and 24 </ b> B communicate with each other through the first expansion chamber 32 in the muffler 26 (a dual length L <b> 2 merging portion is formed). There is no need to provide a communication pipe communicating with the exhaust pipe 24. For this reason, there are few restrictions on arrangement in this exhaust structure 10 for vehicles. Further, as compared with the configuration in which the right bank exhaust pipe 22 and the left bank exhaust pipe 24 are communicated with each other through the communication pipe, the exhaust gases of the banks 14 and 16 are merged in the expansion chambers 32 and 34 having a large cross-sectional area as described above. The output improvement effect by is great.

As described above, in the vehicle exhaust structure 10 according to the first embodiment, restrictions on the arrangement and the like are reduced while the dual length is variable.

  In the vehicle exhaust structure 10, the valve body 46 constituting the opening / closing valves 42 and 44 is disposed in the first expansion chamber 32, and therefore the valve body 46, the right bank exhaust pipe 22, and the left bank exhaust pipe. The requirement for the sealing performance (exhaust gas leakage) with 24 is eased. Further, the valve body 46 (the seal portion) is prevented from being affected by road surface interference, stepping stones, icing, and the like. That is, the valve body 46 is protected. Furthermore, it is difficult to hear external noise such as sliding sound around the support shaft 50 when the opening / closing valves 42 and 44 are operated.

  Further, in the vehicle exhaust structure 10, when the engine 12 is running at a low speed, the exhaust gas discharged from the opening ends 22 </ b> A and 24 </ b> A and joined together is expanded in the two extension chambers 34 and 32. Since it is discharged from the exhaust main pipe 38, in other words, since the expansion ratio is large, the silencing effect by the muffler 26 is great. On the other hand, when the engine 12 is rotating at high speed, the exhaust gas discharged from the through holes 22B and 24B to the first expansion chamber 32 and joined is discharged from the exhaust main pipe 38 by bypassing the second expansion chamber 34 and the communication pipe 40. Therefore, the back pressure (exhaust resistance) is reduced. For this reason, the characteristic of what is called an omission is obtained at the time of high rotation.

  Furthermore, in the vehicle exhaust structure 10, the right bank exhaust pipe 22 and the left bank exhaust pipe 24, which are upstream of the muffler 26, are disposed in the muffler 26 at both low and high engine speeds. Since the first expansion chamber 32 or the second expansion chamber 34 is directly communicated (connected), the exhaust sound pressure does not increase due to resonance of the exhaust pipes 22 and 24 (the peak of the exhaust sound is generated by resonance). There is no).

  Next, another embodiment of the present invention will be described. Note that parts and portions that are basically the same as those in the first embodiment or the previous configuration are denoted by the same reference numerals as those in the first embodiment or the previous configuration, and description thereof is omitted.

[Second Embodiment]
FIG. 7 shows a front sectional view of an on-off valve 66 constituting a vehicle exhaust structure 65 according to a second embodiment of the present invention. As shown in this figure, the opening / closing valve 66 includes a valve body 46 as a first valve body for opening and closing the through hole 22B and a valve body 46 as a second valve body for opening and closing the through hole 24B by a connecting member 68. They are connected to each other and differ from the open / close valves 42 and 44 in that they are driven by a single actuator 48 (not shown) to open and close the through holes 22B and 24B.

  A support shaft 68A is provided in the longitudinal center of the connecting member 68 along the axial direction of the muffler 26. The support shaft 68A is supported by the front plate 26B and the separator 28 so as to be rotatable about its own shaft. Yes. The through holes 22B and 24B are arranged symmetrically with respect to the support shaft 68A in the front view, and similarly, the pair of valve bodies 46 are arranged symmetrically with respect to the support shaft 68A in the front view.

  Thereby, the engine ECU 62 controls the single (common) actuator 48 in the opening / closing valve 66 without opening and closing the two actuators 48 (winding device 60) to open and close the through holes 22B and 24B together (simultaneously). It is configured to be able to. Other configurations of the vehicle exhaust structure 65 are the same as those of the vehicle exhaust structure 10 according to the first embodiment.

  Therefore, the vehicle exhaust structure 65 according to the second embodiment can obtain the same effect by the same operation as that of the first embodiment. Further, the vehicle exhaust structure 65 has a simple structure because the through holes 22B and 24B can be opened and closed by switching the single (common) actuator 48 between operation and non-operation.

[Third Embodiment]
FIG. 8 shows a vehicle exhaust structure 70 according to a third embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 70 differs from the first embodiment only in that a through hole 38B that opens into the third space 36 is formed in the exhaust main pipe 38. The third space 36 in this embodiment is referred to as a third expansion chamber.

  Therefore, the vehicle exhaust structure 70 according to the third embodiment can obtain the same effect by the same operation as that of the first embodiment. Further, in the vehicle exhaust structure 70, the exhaust main pipe 38 has the through hole 38 </ b> A communicating with the third expansion chamber 36, so that the expansion ratio of the muffler 26 is increased. Thereby, the silencing effect by the muffler 26 is improved. In particular, the silencing effect from low to medium rotation speed is improved.

[Fourth Embodiment]
FIG. 9 shows a vehicle exhaust structure 75 according to a fourth embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 75 is different in that the right bank exhaust pipe 22 and the left bank exhaust pipe 24 do not have the through holes 22B and 24B but communicate with each other via the communication pipe 76. Different from the first embodiment.

  The communication pipe 76 communicates the outer (front) part of the muffler 26 in the right bank exhaust pipe 22 and the left bank exhaust pipe 24, and corresponds to a first junction. The length of the right bank exhaust pipe 22 and the left bank exhaust pipe 24 to the communication portion of the communication pipe 76 is a dual length L2. An open / close valve 78 is disposed in the communication pipe 76. The on-off valve 78 includes a valve body (butterfly valve) 80 that can rotate around the support shaft 80A that is supported by the communication pipe 76 to open and close the communication pipe 76, and the communication of the valve body 80 at the support shaft 80A. An actuator 48 is connected to a portion protruding outside the tube 76. The actuator 48 is controlled by the engine ECU 62 in the same manner as in the first embodiment.

  Other configurations of the vehicle exhaust structure 75 are the same as those of the vehicle exhaust structure 10 according to the first embodiment.

  Therefore, the vehicle exhaust structure 75 according to the fourth embodiment is the same as that of the first embodiment except for the effect that the joining portion having the dual length L2 joins through the first expansion chamber 32 of the muffler 26. The same effect can be obtained by the action. Further, in the vehicle exhaust structure 75, even when the longitudinal length of the muffler 26 is configured to be short, the difference L3 between the dual length L1 and the dual length L2 can be set large. Further, in the vehicle exhaust structure 75, the single (common) valve element 80, that is, the opening / closing valve 78, can switch between the merged and non-merged exhaust gas communication pipes 76 of the left and right banks 14, 16; Simple.

[Fifth Embodiment]
FIG. 10 is a plan view showing a vehicle exhaust structure 85 according to the fifth embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 85 is configured in exactly the same way as the first embodiment with respect to the dual-length switching structure. In the following, the configuration and operational effects of the vehicle exhaust structure 85 different from those of the vehicle exhaust structure 10 will be described.

  In this vehicle exhaust structure 85, flexible pipes 86 are interposed immediately before the muffler 26 in the right bank exhaust pipe 22 and the left bank exhaust pipe 24. Further, the right bank exhaust pipe 22 and the left bank exhaust pipe 24 are connected by a bracket 88 and supported by the vehicle body immediately before the installation site of the flexible pipe 86.

  As shown in FIG. 11C, the bracket 88 penetrates both the right bank exhaust pipe 22 and the left bank exhaust pipe 24 in the radial direction, and circulates in the right bank exhaust pipe 22 and the left bank exhaust pipe 24. It is set as the structure which contacts the exhaust gas which does. Specifically, as shown in FIG. 11A, the right bank exhaust pipe 22 and the left bank exhaust pipe 24 are respectively composed of an engine side exhaust pipe 90 and a flexible pipe 86 that constitute a front portion of the flexible pipe 86. Also, a muffler-side exhaust pipe 92 constituting the rear portion is connected via a flexible pipe 86.

  Further, as shown in FIGS. 11 (A) and 11 (C), at the rear end of the engine-side exhaust pipe 90, slits 90A opening rearward are formed at two locations where the relative position on the pipe wall is 180 °. Has been. The longitudinal length of the slit 90 </ b> A is made larger than the width of the bracket 88. The bracket 88 is fitted in each slit 90A arranged in a straight line when viewed from the front of the right bank exhaust pipe 22 and the left bank exhaust pipe 24, and a flexible pipe 86 is fitted to the rear end of the engine side exhaust pipe 90. To prevent it from coming off. A gap between the edge of the slit 90A and the bracket 88 is appropriately sealed by welding or the like.

  In the bracket 88 described above, as shown in FIG. 11C, the portions located in the right bank exhaust pipe 22 and the left bank exhaust pipe 24 serve as the exhaust gas cooling section 88A, and the right bank exhaust pipe 22 and the left bank exhaust pipe are located. A portion located outside the tube 24 is a cooled portion 88B.

  Further, in the vehicle exhaust structure 85, a dynamic damper (dynamic vibration absorber) 94 is provided on the bracket 88. The dynamic damper 94 includes a mass portion 94A and a stay portion (plate spring) 94B that connects the mass portion 94A and the bracket 88, and is tuned to suppress vibration of the flexible pipe 86 when the engine 12 is idle. ing.

  In the vehicle exhaust structure 85 described above, the exhaust gas flowing through the right bank exhaust pipe 22 and the left bank exhaust pipe 24 is generated by the bracket 88 in which the cooled portion 88B is cooled by the traveling wind that comes into contact with the traveling of the vehicle. It contacts the exhaust gas cooling section 88A and is cooled before joining. As a result, the temperature of the exhaust gas is lowered, and the propagation speed of the exhaust pulsation, that is, the blowdown wave and the reflected negative pressure wave is lowered. That is, the same effect as that obtained by increasing the dual length is obtained.

  Therefore, with the configuration in which the dual length L2 is short, it is possible to obtain the torque improvement effect at the time of low rotation equivalent to the configuration in which the dual length L2 is long (the configuration not including the cooling means). Further, the torque increase effect at the time of high rotation can be realized with the short dual length L1 in accordance with the exhaust temperature decreasing. That is, by providing the bracket 88 as a cooling means, the vehicle exhaust structure 85 can be made compact.

  This configuration is also preferably applied when the engine 12 is a horizontal engine.

[Sixth Embodiment]
FIG. 12 shows a vehicle exhaust structure 95 according to a sixth embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 95 is configured such that a part of independent flow paths of the right bank 14 and the left bank 16 is constituted by a θ pipe 96 which is a divided pipe common to the banks 14 and 16. This is different from the above embodiments. This will be specifically described below.

  The θ pipe 96 is provided along the longitudinal direction thereof, and includes a partition wall 96B that partitions the internal space of the pipe body 96A formed in a cylindrical shape into two substantially semi-cylindrical spaces that are symmetrical to each other. One space in the θ pipe 96 is referred to as a right bank side flow path 98, and the other space is referred to as a left bank side flow path 100.

  The θ pipe 96 is connected at its front end so that the rear end (corresponding to the opening end 22A) of the right bank exhaust pipe 22 communicates with the right bank side flow path 98, and the rear end of the left bank exhaust pipe ( (Corresponding to the opening end 24A) is connected so as to communicate with the left bank-side channel 100. The rear portion of the θ pipe 96 passes through the front plate 26B and the front and rear separators 28 and 30 in an airtight state and is introduced into the second expansion chamber 34 of the muffler 26.

  The rear opening end 96C of the θ pipe 96 that opens in the second expansion chamber 34, that is, the portion having the dual length L1 is respectively provided in the second opening and the second merging portion of the first and second exhaust pipes in the present invention. Equivalent to. As shown in FIG. 13, the partition 96 </ b> B of the θ pipe 96 is provided with a first opening that is opened and closed by the opening / closing valve 102 and a communication window 104 as a first junction.

  The communicating window 104 has a height in the vertical direction substantially equal to the inner diameter of the pipe body 96A, and a width along the front-rear direction is sufficiently smaller than the inner diameter of the pipe body 96A. As shown in FIG. 12, the communication window 104 is disposed in a portion having the dual length L <b> 1. In this embodiment, the communication window 104 is disposed in a portion of the θ pipe 96 positioned in the first expansion chamber 32.

  The on-off valve 102 includes a valve body (butterfly valve) 106 that can rotate around a support shaft 106A that is supported by the pipe body 96A to open and close the communication window 104, and protrudes from the pipe body 96A at the support shaft 106A. An actuator 48 is connected to the part. The actuator 48 is controlled by the engine ECU 62 in the same manner as in the first embodiment.

  Other configurations of the vehicle exhaust structure 95 are the same as those of the vehicle exhaust structure 10 according to the first embodiment.

  Therefore, the vehicular exhaust structure 95 according to the sixth embodiment also has the same effect as that of the first embodiment except for the effect that the joining portion having the dual length L2 joins through the first expansion chamber 32 of the muffler 26. The same effect can be obtained by the action. Further, in the vehicle exhaust structure 95, even when the longitudinal length of the muffler 26 is configured to be short, the difference L3 between the dual length L1 and the dual length L2 can be set large. Further, the vehicle exhaust structure 95 has a simple structure because the exhaust gas merging and non-merging of the left and right banks 14 and 16 can be switched by a single (common) valve element 106, that is, the opening / closing valve 102.

  In the vehicle exhaust structure 95, since the right bank side flow path 98 and the left bank side flow path 100 are formed in one θ pipe 96, the two right bank exhaust pipes 22 and the left bank exhaust pipe 24 have a full length. Compared with the structure which forms the flow path before the merge of each bank 14 and 16, the surface area of the part exposed outside the vehicle in the flow path wall constituting the flow path is small, and the heat capacity is also small. For this reason, in the configuration using the θ pipe 96, the temperature of the exhaust gas tends to rise, and the propagation speed of the exhaust pulsation, that is, the blowdown wave and the reflected negative pressure wave tends to increase. Therefore, in the vehicle exhaust structure 95, the time until the output improvement effect occurs after the engine 12 is started is shortened.

  This will be described with reference to the diagram shown in FIG. FIG. 14 shows the relationship between the elapsed time from the start of the engine 12 and the exhaust gas temperature at the exhaust gas merging portion (the position of the dual length L1 or L2) in the left and right banks 14 and 16. A temperature range Rt indicated by hatching is an exhaust gas temperature range in which the reflected negative pressure wave of the own cylinder is synchronized with the valve overlap timing at a specific rotation speed of the engine 12, and the exhaust gas temperature is within the temperature range Rt. In this case, the dual lengths L1 and L2 are set so that the output improvement effect of the engine 12 can be obtained. For example, when the exhaust gas temperature is less than the lower limit of the temperature range Rt, the reflected negative pressure wave of the own cylinder is synchronized with the valve overlap timing at a rotational speed lower than the specific rotational speed.

  14 shows the exhaust gas temperature rise of the vehicle exhaust structure 95 using the θ pipe 96, and the solid line shows the two right bank exhaust pipes 22 and the left The exhaust gas temperature rise of the comparative example (for example, vehicle exhaust structure 10 etc.) in which the bank exhaust pipe 24 forms the flow path before the merge of the banks 14 and 16 over the entire length is shown.

  From this figure, in the vehicle exhaust structure 95 according to the sixth embodiment, by using the θ pipe 96, the time T1 until the exhaust gas temperature reaches the temperature range Rt is shown. It can be seen that it is shorter than the time T2 to reach the temperature range Rt. As a result, in the vehicle exhaust structure 95, after the engine 12 is started, the time until the output improvement effect is produced is shortened as described above.

[Seventh Embodiment]
FIG. 15 shows an exhaust structure 110 for a vehicle according to a seventh embodiment of the present invention. As shown in this figure, in the vehicle exhaust structure 110, the pipe body 96A of the θ pipe 96 has a first opening having a dual length L1, a first joining portion, and a through hole 112 serving as a tube wall penetration portion. Is different from the sixth embodiment in which the communication window 104 is formed in the partition wall 96B.

  As shown in FIGS. 16A and 16B, the through holes 112 are formed to open on both sides in the circumferential direction across the partition wall 96B of the pipe body 96A of the θ pipe 96. Therefore, in the vehicle exhaust structure 110, the right bank side flow path 98 and the left bank side flow path 100 merge through the first expansion chamber 32 when the through hole 112 is opened.

  In the vehicle exhaust structure 110, the through hole 112 is opened and closed by the opening / closing valve 114. The on-off valve 114 includes a first valve body and a valve body 116 as a second valve body formed in an arc shape along the outer peripheral surface of the pipe body 96 </ b> A when viewed from the axial direction of the θ pipe 96. The valve body 116 is rotatably supported by a shaft support portion 118 fixed to the pipe body 96A via a support shaft 120 in a bearing portion 116A extending in the circumferential direction from both circumferential ends at the front end. ing.

  The valve body 116 can take a closed position for closing the through hole 112 and an open position for opening the through hole 112 by turning around the support shaft 120. One spindle 120 passes through the muffler cylinder 26A and protrudes out of the muffler 26, and an actuator 48 is connected to the protruding portion.

  Other configurations of the vehicle exhaust structure 110 are the same as those of the vehicle exhaust structure 95 according to the sixth embodiment.

  Therefore, also by the vehicle exhaust structure 110 according to the seventh embodiment, the same effect can be obtained by the same operation as that of the sixth embodiment. Further, in the vehicle exhaust structure 110, when the dual length L2 is selected, the exhaust gases of the left and right banks 14 and 16 merge in the first expansion chamber 32. Therefore, the same operation is performed by the same operation as in the first embodiment. An effect can be obtained.

[Eighth Embodiment]
FIG. 17 shows a part of the vehicle exhaust structure 125 according to the eighth embodiment of the present invention. As shown in this figure, in the vehicle exhaust structure 125, the pipe body 96A of the θ pipe 96 has a first opening having a dual length L1 and a pair of through holes 126, 128 serving as a first junction. This is different from the seventh embodiment in which a single through hole 112 is formed.

  The through holes 126 and 128 are formed independently of each other on the opposite sides of the partition wall 96B in the pipe body 96A, and open in the first expansion chamber 32. FIG. 17 illustrates a configuration in which only one of the separators 28 and 30 is provided and the third space 36 is not formed. However, as a configuration in which the third space (third expansion chamber) 36 is formed. It goes without saying that it is also good.

  The through holes 126 and 128 are opened and closed by opening and closing valves 130 and 132, respectively. As shown in FIG. 18, the open / close valves 130 and 132 include valve bodies 134 that are formed in circular arcs that are symmetrical with each other along the outer peripheral surface of the pipe main body 96 </ b> A when viewed from the axial direction of the θ pipe 96. The valve body 134 is rotatably supported by the pipe body 96 </ b> A via a support shaft 136 in a bearing portion 134 </ b> A that extends forward from both circumferential ends at the front end.

  The valve body 134 of each open / close valve 130, 132 can take a closed position for closing the through-holes 126, 128 and an open position for opening the through-holes 126, 128 by turning around the respective support shafts 136. It has become. The support shaft 136 protrudes out of the muffler 26 through the muffler cylinder 26A, and an actuator 48 is connected to the protruding portion.

  Other configurations of the vehicle exhaust structure 110 are the same as those of the vehicle exhaust structure 110 according to the seventh embodiment.

  Therefore, the vehicle exhaust structure 110 according to the eighth embodiment also has the seventh embodiment except for the effect of having one on-off valve 114 (actuator 48) that is driven when the dual length L2 is selected. The same effect can be obtained by the same action as the form.

  In this embodiment, instead of the opening / closing valves 130 and 132 for opening and closing the through holes 126 and 128, the opening / closing valves 42 and 44 whose mounting directions are changed may be provided in the common θ pipe 96.

[Ninth Embodiment]
FIG. 19A schematically shows a vehicle exhaust structure 140 according to the ninth embodiment of the present invention, and FIG. 19B shows a part of the vehicle exhaust structure 140. ing. As shown in these drawings, the vehicle exhaust structure 140 has the seventh and third aspects in that the muffler 26 has a single expansion chamber 142 and the open end 96C of the θ pipe 96 is located on the outer rear side of the muffler 26. Different from the eighth embodiment. The ninth embodiment is common to the seventh embodiment in that a through-hole 112 that is opened and closed by an opening / closing valve 114 is provided in the θ pipe 96.

  The muffler 26 is configured such that the front and rear open ends of the muffler cylinder 26A are closed by a front plate 26B and a rear plate 26C, respectively, and the inside is a single expansion chamber 142. The θ pipe 96 penetrates both the front plate 26B and the rear plate 26C. The right bank exhaust pipe 22 and the left bank exhaust pipe 24 are connected in front of the muffler 26, and the through hole 112 is formed in the expansion chamber 142. Has been placed.

  The rear end of the θ pipe 96 is joined directly to the front end of the exhaust main pipe 38. Other configurations of the vehicle exhaust structure 140 are the same as those of the vehicle exhaust structure 110 according to the seventh embodiment.

  Therefore, also in the vehicle exhaust structure 140 according to the ninth embodiment, when the dual length L1 is selected, the exhaust gas merging portion of the left and right banks 14, 16 is the second expansion chamber 34 of the muffler 26. Except for the function and effect, the same effect can be obtained by the same function as in the seventh embodiment.

  Further, in the vehicle exhaust structure 140, when the dual length L1 is selected, the expansion chamber 142 where the exhaust gases of the left and right banks 14 and 16 merge has a large cross-sectional area and an expansion ratio increases, so that the reflection negative of the own cylinder is increased. The pressure wave increases. For this reason, the output improvement effect at the time of high rotation which synchronizes this reflected negative pressure wave with valve overlap timing increases. Furthermore, in the configuration in which the front and rear length (full length) of the muffler 26 is short, the difference L3 between the dual length L1 and the dual length L2 can be set large.

[Tenth embodiment]
FIG. 20 shows a part of a vehicle exhaust structure 145 according to a tenth embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 145 has a right bank side channel 98 instead of a single through hole 112 that opens the right bank side channel 98 and the left bank side channel 100 in the expansion chamber 142. 98, which differs from the ninth embodiment in that it includes through holes 126 and 128 that allow the left bank-side channel 100 to be opened independently in the expansion chamber 142.

  In the vehicle exhaust structure 145, the through holes 126 and 128 are opened and closed by the opening and closing valves 42 and 44. The on-off valves 42 and 44 are provided symmetrically with respect to the partition wall 96 </ b> B in a common θ pipe 96. Other configurations of the vehicle exhaust structure 140 are the same as those of the vehicle exhaust structure 140 according to the ninth embodiment.

  Therefore, the vehicle exhaust structure 145 according to the tenth embodiment also has the ninth implementation except for the effect of having one on-off valve 114 (actuator 48) that is driven when the dual length L2 is selected. The same effect can be obtained by the same action as the form. In this embodiment, on-off valves 130 and 132 may be provided in place of the on-off valves 42 and 44 that open and close the through holes 126 and 128.

[Eleventh embodiment]
FIG. 21 shows a part of a vehicle exhaust structure 150 according to an eleventh embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 150 is different from the ninth embodiment in that a resonance pipe 152 is provided in the expansion chamber 142 of the muffler 26 so as to surround the through hole 112 and the valve body 116. .
The resonance pipe 152 is formed in a cylindrical shape, and is disposed so as to cover the installation site of the through hole 112 in the θ pipe 96 from the outside in the radial direction in a non-contact manner. The resonance pipe 152 has a resonance opening 152 </ b> A that is closed at one end in the axial direction (a radially outer portion of the θ pipe 96) and is open at the other end in the axial direction to communicate with the expansion chamber 142. Thereby, the muffler 26 is configured to obtain a resonance effect. Other configurations of the vehicle exhaust structure 150 are the same as those of the vehicle exhaust structure 140 according to the ninth embodiment.

  Therefore, also by the vehicle exhaust structure 150 according to the eleventh embodiment, the same effect can be obtained by the same operation as in the ninth embodiment. In the vehicle exhaust structure 150, since the resonance pipe 152 is provided, the space in the muffler 26 can be used as a resonance chamber. For this reason, the muffling effect at a specific frequency (engine speed) can be improved by appropriately setting the length and diameter of 152.

[Twelfth embodiment]
FIG. 22 (A) schematically shows a vehicle exhaust structure 155 according to a twelfth embodiment of the present invention, and FIG. 22 (B) shows a part of the vehicle exhaust structure 155. ing. As shown in these drawings, the vehicle exhaust structure 155 has the above-described embodiments in that the rear end 96C of the θ pipe 96 is connected to the exhaust main pipe 38 on the front side (exhaust gas upstream side) of the muffler 26. Different from form.

  A communication window 104 formed in the partition wall 96 </ b> B is disposed at a position where the dual length of the θ pipe 96 is the length L <b> 1, and the communication window 104 is opened and closed by the opening / closing valve 102. Therefore, in the vehicle exhaust structure 155, the exhaust gas merges without passing through the space in the muffler 26 regardless of which of the dual lengths L 1 and L 2 is selected.

  Other configurations of the vehicle exhaust structure 155 are the same as those of the vehicle exhaust structure 140 according to the ninth embodiment.

  Therefore, also in the vehicle exhaust structure 155 according to the eleventh embodiment, when the dual length L2 is selected, the exhaust gas merging portion of the left and right banks 14 and 16 is the first expansion chamber 32 of the muffler 26. Except for the function and effect, the same effect can be obtained by the same function as in the ninth embodiment.

[Thirteenth embodiment]
FIG. 23 shows a vehicle exhaust structure 160 according to a thirteenth embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 160 is different from the first embodiment in that the on-off valves 162 and 164 for opening and closing the through holes 22B and 24B are not controlled by the engine ECU 62.

  Each of the on-off valves 162 and 164 does not include the actuator 48 but includes a valve body 46 that is supported by the shaft support portion 49 so as to be rotatable around the support shaft 50. As shown in FIGS. 24A and 24B, a return spring 166 is disposed between the valve body 46 and the right bank exhaust pipe 22 and the left bank exhaust pipe 24. Due to the urging force of the return spring 166, the valve body 46 is held in the closed position shown in FIG.

  When the exhaust pressure (internal pressure) in the right bank exhaust pipe 22 and the left bank exhaust pipe 24 increases as the engine speed increases, the valve body 46 that has received the internal pressure opens as shown in FIG. It moves to the position. The spring constant of the return spring 166 is set so that the valve body 46 moves to the open position at a predetermined rotational speed.

  Other configurations of the vehicle exhaust structure 160 are the same as those of the vehicle exhaust structure 10 according to the first embodiment.

  In the vehicle exhaust structure 160 described above, a dual-length switching structure is configured in the muffler 26 as in the vehicle exhaust structure 10, and therefore, except for the effect of controlling the dual-length switching. A similar effect can be obtained by the same operation as that of the first embodiment.

  Further, since the vehicle exhaust structure 160 does not include the actuator 48, the dual-length switching structure is realized with a configuration with a small number of parts and low cost. Further, in the vehicle exhaust structure 160, since the opening / closing valves 162 and 164 can be accommodated in the muffler 26 as a whole, the structure is simple and the protection of the opening / closing valves 162 and 164 is high.

  Furthermore, in the vehicle exhaust structure 160, when the internal pressures of the right bank exhaust pipe 22 and the left bank exhaust pipe 24 become high, the open / close valves 162 and 164 open the through holes 22B and 24B, so that the exhaust gas flows into the first expansion chamber 32. To the exhaust main pipe 38. Thereby, reduction of the back pressure at the time of high rotation is achieved automatically.

[Fourteenth embodiment]
FIG. 25 shows a vehicle exhaust structure 170 according to a fourteenth embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 170 is different from the sixth embodiment in that the opening / closing valve 172 for opening / closing the communication window 104 provided in the partition wall 96B of the θ pipe 96 is not controlled by the engine ECU 62. Is different.

  The on-off valve 172 includes a valve body 174 that opens and closes the communication window 104 by rotating along the partition wall 96B. As shown in FIGS. 26 (A) and 26 (B), in this embodiment, the valve body 174 is disposed in the left bank side channel 100. A flat plate portion 174A that can close the communication window 104, a support portion 174B that is rotatably supported by the partition wall 96B by a support pin 176, and a flat plate portion 174A that protrudes from the downstream side in the gas flow direction to the left bank side channel 100 side. Gas receiving part 174C.

  A return spring (not shown) is disposed between the partition wall 96 </ b> B and the valve body 174 around the support pin 176. Due to the urging force of the return spring, the valve body 174 is held in the closed position shown in FIG. When the exhaust pressure (internal pressure) in the right bank side flow path 98 and the left bank side flow path 100 increases as the engine speed increases, the valve body 174 that receives this internal pressure in the gas receiving portion 174C is shown in FIG. It moves to the open position shown in 26 (B). The spring constant of the return spring is set so that the valve body 174 moves to the open position at a predetermined rotational speed.

  Other configurations of the vehicle exhaust structure 170 are the same as those of the vehicle exhaust structure 95 according to the sixth embodiment.

  Therefore, in the vehicle exhaust structure 170 described above, the same effect can be obtained by the same operation as that of the sixth embodiment except for the operation due to the control accompanying the switching of the dual length. Further, the operation and effect obtained when the on-off valve 172 is operated by the pressure of the exhaust gas is the same as the operation and effect in the thirteenth embodiment.

[Fifteenth embodiment]
FIG. 27A shows a part of a vehicle exhaust structure 180 according to the fifteenth embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 180 is such that the opening and closing valves 182 and 184 for opening and closing the pair of through holes 126 and 128 provided in the pipe body 96A of the θ pipe 96 are not controlled by the engine ECU 62. This is different from the tenth embodiment.

  As shown in FIGS. 27B and 27C, the on-off valves 182 and 184 are each provided with a valve body 46, a shaft support portion 49, a support shaft 50, and a return spring 166, and the on-off valves 162 and 164 are provided. Is provided adjacent to the common pipe body 96A in the circumferential direction. Accordingly, when the exhaust pressure (internal pressure) in the right bank side flow path 98 and the left bank side flow path 100 rises as the engine speed increases, the on-off valves 182 and 184 The through holes 126 and 128 are opened.

  Other configurations of the vehicle exhaust structure 180 are the same as those of the vehicle exhaust structure 145 according to the tenth embodiment.

  Therefore, in the vehicle exhaust structure 170 described above, the same effect can be obtained by the same operation as that of the tenth embodiment, except for the operation due to the control accompanying the switching of the dual length. Further, the operation and effect obtained when the on-off valves 182 and 184 are operated by the pressure of the exhaust gas are the same as those in the thirteenth and fourteenth embodiments.

[Sixteenth Embodiment]
FIG. 28 shows an exhaust structure 190 for a vehicle according to a sixteenth embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 190 is different from the first embodiment in that an engine ECU 192 is provided instead of the engine ECU 62.

  The engine ECU 192 is electrically connected to the winding device 60 of the on-off valves 42 and 44 and the rotation detector 64 and is also electrically connected to an exhaust temperature sensor 194 disposed in the right bank exhaust pipe 22. . The exhaust temperature sensor 194 is configured to output a signal corresponding to the temperature of the exhaust gas to the engine ECU 192, and may be provided in the left bank exhaust pipe 24.

  Other mechanical configurations of the vehicle exhaust structure 190 are the same as those of the vehicle exhaust structure 10 according to the first embodiment. On the other hand, the engine ECU 192 is configured to perform dual length switching control based on signals from the rotation detector 64 and the exhaust temperature sensor 194.

  This control concept will be described. FIG. 29 is a diagram showing a calculation result indicating the optimum dual length with respect to the engine speed, that is, the dual length at which the reflected negative pressure wave of the own cylinder is synchronized with the valve overlap timing. The “◯” plot is a calculation result when the exhaust gas temperature is relatively low, and the “x” plot is a calculation result when the exhaust gas temperature is relatively high.

  From this figure, it can be seen that the optimum dual length becomes longer at a high temperature when the propagation speed of the pulsation, that is, the reflected negative pressure wave becomes faster. Therefore, in the dual length switching control, the engine output improvement effect can be increased by changing the switching point, that is, the engine speed (threshold value) for switching the dual length in accordance with the exhaust gas temperature.

  Here, for example, at each exhaust gas temperature, a rotational speed Ns [rpm] intermediate between the rotational speed at which the dual length L1 is the optimal dual length and the rotational speed at which the dual length L2 is the optimal dual length is used as a switching point. In this case, the propagation speed of pulsation is C [m / s], the temperature of exhaust gas is t [K], the dual length to be switched is L1 [m], L2 [m], and the coefficient determined by the valve timing and the shape of the exhaust flow path Assuming that K is C = 20√t, the rotation speed Ns of the switching point is Ns = (K × √t / (L1 + L2)).

  As the coefficient K, for example, 600 can be adopted. Nsl shown in FIG. 29 is a switching point at a low temperature indicated by a “◯” plot, and Nsh is a switching point at a high temperature indicated by a “×” plot. The pulsation propagation velocity C is approximately 620 [m / s] when the exhaust gas temperature is 700 ° C. and approximately 480 [m / s] when the exhaust gas temperature is 300 ° C.

  A control flow by the engine ECU 192 is shown as a flowchart in FIG. At the time when the engine 12 is started in step S10 and the vehicle starts running, the open / close valves 42 and 44 are closed in the through holes 22B and 24B, and the dual length L1 is selected. In step S12, the rotational speed of the engine 12 detected based on the signal from the rotation detector 64 is compared with the switching point Ns calculated using the signal from the exhaust temperature sensor 194, that is, the exhaust gas temperature t. When it is determined that the actual engine speed N is equal to or less than the switching point Ns, the state where the dual length L1 is selected is maintained.

  When it is determined that the engine speed N exceeds the switching point Ns, the process proceeds to step S14 and the dual length L2 is selected. That is, the open / close valves 42 and 44 open the through holes 22B and 24B. Next, the process proceeds to step S16, and it is determined whether or not the actual engine speed N is below the switching point Ns. When it is determined that the rotational speed N is equal to or higher than the switching point Ns, the state where the dual length L2 is selected is maintained. On the other hand, if it is determined that the rotational speed N is lower than the switching point Ns, the process proceeds to step S18 and the dual length L1 is selected. That is, the through holes 22B and 24B are closed by the opening and closing valves 42 and 44.

  In this embodiment, the engine ECU 192 does not calculate the switching point Ns according to the exhaust gas temperature, but selects the switching point Ns that is set and stored according to the exhaust gas temperature and compares it with the actual rotational speed N. It has become. The exhaust gas temperature and the switching point Ns are stored as a map.

  In the vehicle exhaust structure 190 described above, since the dual-length switching structure is configured in the muffler 26 as in the vehicle exhaust structure 10, the same effect can be obtained by the same operation as in the first embodiment. Can do.

  Further, in the vehicle exhaust structure 190, the dual length switching point is changed according to the exhaust gas temperature, so that a more appropriate dual length is selected according to the propagation speed of the pulsation (blowdown wave, reflected negative pressure wave). Is possible. In other words, an engine output improvement effect equivalent to the configuration in which the dual length is switched in multiple stages can be obtained.

  The control by the engine ECU 192 can be employed in place of the control by the engine ECU 62 in each of the first to twelfth embodiments. In this case, the effect by control of engine ECU192 can be acquired, maintaining the effect by the mechanical characteristic in each embodiment. And this control is applicable also to the exhaust structure for vehicles which has the dual length switching structure which is not contained in this invention as a mechanical structure like 17th and 18th embodiment shown below.

[Seventeenth embodiment]
FIG. 31 schematically shows an exhaust structure 200 for a vehicle according to a seventeenth embodiment of the present invention. As shown in this figure, the vehicle exhaust structure 200 is such that the right bank exhaust pipe 22 and the left bank exhaust pipe 24 are connected to the exhaust main pipe 38 on the front side (exhaust gas upstream side) of the muffler 26. This is different from the fourth embodiment.

  In the vehicle exhaust structure 200, the connecting portion of the right bank exhaust pipe 22 and the left bank exhaust pipe 24 to the exhaust main pipe 38 is a second junction having a dual length L 1. The communication part by the communication pipe 76 with the left bank exhaust pipe 24 is a first junction part having a dual length of length L2. The opening / closing valve 78 that opens and closes the communication pipe 76 is controlled by the engine ECU 192.

  Other configurations of the vehicle exhaust structure 200 are the same as those of the vehicle exhaust structure 75 according to the fourth embodiment.

  In the vehicle exhaust structure 200 described above, since the opening / closing valve 78 is controlled by the engine ECU 192, the exhaust gases of the left and right banks 14, 16 merge through the internal space of the muffler 26 in any of the dual-length switching states. The effect similar to the vehicle exhaust structure 190 which concerns on 16th Embodiment, ie, the effect by control of engine ECU192, can be acquired except the effect by.

[Eighteenth Embodiment]
FIG. 32A schematically shows a vehicle exhaust structure 210 according to an eighteenth embodiment of the present invention. As shown in this figure, in the vehicle exhaust structure 210, the exhaust gas confluence G of the left and right banks 14 and 16 is one place at the front end of the exhaust main pipe 38. It is different from the above embodiments in that the dual length is switched by switching the route (route length).

  A flow path switching unit 212 is provided in the middle part of the right bank exhaust pipe 22 and the left bank exhaust pipe 24, and a short distance between the branching section 212A and the merging section 212B in the flow path switching section 212. A channel 214 and a long channel 216 are provided. An open / close valve 78 controlled by the engine ECU 192 is disposed in the short flow path of each flow path switching unit 212. Thereby, when the open / close valve 78 opens the short flow path 214, the short dual length L2 via the short flow path 214 becomes the length until the left and right banks 14 and 16 merge, and the open / close valve 78 is When the short flow path 214 is closed, the long dual length L1 via the long flow path 216 is a length until the left and right banks 14 and 16 merge.

  A specific example of the flow path switching unit 212 will be described. As illustrated in FIG. 32B, the flow path switching unit 212 includes an outer housing 218, an inner pipe 220 provided coaxially in the outer housing 218, The front end is inserted into the rear end side of the inner pipe 220 coaxially and in a non-contact manner, and the rear end side includes an outlet pipe portion 222 that protrudes from the rear end of the outer housing 218 in an airtight state. The open / close valve 78 is disposed in the inner pipe 220.

  A path through which exhaust gas flows linearly from the branch portion 212A, which is the inlet portion of the outer housing 218, to the junction portion 212B via the inner pipe 220 and the outlet pipe portion 222 (indicated by a two-dot chain line in FIG. 32B). (See arrow) is a short flow path 214. On the other hand, a path from the branching part 212A to the outside of the inner pipe 220, the overlap part of the inner pipe 220 and the outlet pipe part 222, and the junction part 212B via the outlet pipe part 222 (shown by the solid line in FIG. 32B). The long flow path 216 is indicated by an arrow).

  In the vehicle exhaust structure 210 described above, the open / close valve 78 of each flow path switching unit 212 is controlled synchronously by the engine ECU 192, and therefore, the left and right banks through the internal space of the muffler 26 in any of the dual length switching states. Except for the effect of the exhaust gases 14 and 16 merging, the same effect as the vehicle exhaust structure 190 according to the sixteenth embodiment, that is, the effect of the control of the engine ECU 192 can be obtained.

  In each of the above embodiments, an example in which the dual length is automatically switched by the control of the engine ECU 62 or the engine ECU 192 or by the pressure of the exhaust gas is shown, but the present invention is not limited to this, and for example, the first In the configurations of the first to sixteenth embodiments, the dual length is switched by the driver's hand switch operation together with or instead of the dual length switching means based on the control or exhaust gas pressure described above. It is also possible. In this configuration, depending on the driver's preference, select whether to shorten the dual length and improve the maximum output of the engine 12, or to increase the dual length and increase the torque in the low / medium speed region of the engine rotation. It becomes possible to do.

  The present invention is not limited to the above embodiments, and can be implemented with various modifications. Needless to say, the constituent elements of the above-described embodiments (for example, the structure of the on-off valve, etc.) can be appropriately combined.

1 is a cross-sectional plan view illustrating a vehicle exhaust structure according to a first embodiment of the present invention. It is a perspective view which shows the on-off valve which comprises the vehicle exhaust structure which concerns on the 1st Embodiment of this invention. It is a figure which shows the switching state of the dual length by the on-off valve which comprises the exhaust structure for vehicles which concerns on the 1st Embodiment of this invention, Comprising: (A) is a perspective view of the state as which the long dual length was selected, (B) ) Is a perspective view in a state where a short dual length is selected. It is a schematic diagram showing an exhaust pulsation transmission path in an engine to which the vehicle exhaust structure according to the first embodiment of the present invention is applied. It is a timing chart which shows operation | movement of the engine to which the exhaust structure for vehicles which concerns on the 1st Embodiment of this invention was applied. It is a diagram which shows the dual length switching point by the exhaust structure for vehicles which concerns on the 1st Embodiment of this invention. It is front sectional drawing which shows the on-off valve which comprises the exhaust structure for vehicles which concerns on the 2nd Embodiment of this invention. It is a plane sectional view showing the exhaust structure for vehicles concerning a 3rd embodiment of the present invention. It is a plane sectional view showing the exhaust structure for vehicles concerning a 4th embodiment of the present invention. It is a top view which shows the exhaust structure for vehicles which concerns on the 5th Embodiment of this invention. It is a figure which shows the assembly | attachment structure of the bracket which comprises the exhaust structure for vehicles which concerns on the 5th Embodiment of this invention, (A) is a decomposition | disassembly side view, (B) is a side view, (C) is FIG. It is sectional drawing along the 11C-11C line of (B). It is a plane sectional view showing the exhaust structure for vehicles concerning the 6th embodiment of the present invention. It is a perspective view which shows the on-off valve which comprises the exhaust structure for vehicles which concerns on the 6th Embodiment of this invention. It is a diagram which shows the relationship between the elapsed time from engine starting, and exhaust gas temperature for demonstrating the effect by (theta) pipe which comprises the exhaust structure for vehicles which concerns on the 6th Embodiment of this invention. It is a plane sectional view showing the exhaust structure for vehicles concerning a 7th embodiment of the present invention. It is a figure which shows the on-off valve which comprises the exhaust structure for vehicles which concerns on the 7th Embodiment of this invention, Comprising: (A) is a perspective view, (B) is sectional drawing. It is a plane sectional view showing a part of the exhaust system for vehicles concerning the 8th embodiment of the present invention. It is a perspective view which shows the on-off valve which comprises the exhaust structure for vehicles which concerns on the 8th Embodiment of this invention. It is a figure which shows the exhaust structure for vehicles which concerns on the 9th Embodiment of this invention, Comprising: (A) is a schematic diagram, (B) is a plane sectional view of the principal part. It is a plane sectional view of the important section of the exhaust system for vehicles concerning a 10th embodiment of the present invention. It is a plane sectional view of the important section of the exhaust structure for vehicles concerning an 11th embodiment of the present invention. It is a figure which shows the exhaust structure for vehicles which concerns on the 12th Embodiment of this invention, Comprising: (A) is a schematic diagram, (B) is a plane sectional view of the principal part. It is a top sectional view of the exhaust structure for vehicles concerning the 13th embodiment of the present invention. It is a figure which shows the switching state of the dual length by the on-off valve which comprises the exhaust structure for vehicles which concerns on the 13th Embodiment of this invention, Comprising: (A) is a perspective view of the state as which the long dual length was selected, (B ) Is a perspective view in a state where a short dual length is selected. It is a plane sectional view of the exhaust structure for vehicles concerning a 14th embodiment of the present invention. It is a figure which shows the switching state of the dual length by the on-off valve which comprises the exhaust structure for vehicles which concerns on the 14th Embodiment of this invention, Comprising: (A) is a perspective view of the state as which the long dual length was selected, (B) ) Is a perspective view in a state where a short dual length is selected. It is a figure which shows the exhaust structure for vehicles which concerns on 15th Embodiment of this invention, Comprising: (A) is a plane sectional view of the principal part, (B) is a perspective view of an on-off valve, (C) is a cross section of an on-off valve. FIG. It is a top sectional view of the exhaust structure for vehicles concerning the 16th embodiment of the present invention. It is a diagram which shows the dual length switching point by the exhaust structure for vehicles which concerns on the 16th Embodiment of this invention. It is a flowchart which shows the control flow of the exhaust structure for vehicles which concerns on the 16th Embodiment of this invention. It is a schematic diagram which shows the exhaust structure for vehicles which concerns on the 17th Embodiment of this invention. It is a figure which shows the exhaust structure for vehicles which concerns on the 18th Embodiment of this invention, Comprising: (A) is a schematic diagram, (B) is sectional drawing which shows the specific structural example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Exhaust structure for vehicles 12 Internal combustion engine 14 Right bank (1st bank)
16 Left bank (second bank)
22 Right bank exhaust pipe (first exhaust pipe, one of the two exhaust passages)
22A Open end (second opening, second junction)
22B Through hole (first opening, first junction)
24 Left bank exhaust pipe (second exhaust pipe, one of two exhaust paths)
24A Open end (second opening, second junction)
24B Through hole (first opening, first junction)
26 Muffler 28/30 Separator 32 First expansion chamber (first space, space or other space)
34 Second expansion room (second space, space or other space)
42 Open / close valve (open / close means, exhaust merging length switching means)
46 Valve body (first valve body, second valve body)
48 Actuator 64 Rotation detector (Rotation speed detection means)
65, 70, 75, 85, 95, 110, 125, 140, 145, 150, 155, 160, 170, 180, 190, 200, 210 Exhaust structure for vehicle 66, 114 Open / close valve (open / close means, open / close valve device, Exhaust merge length switching means)
78, 102, 130, 132, 162, 164, 172, 182, 184 Open / close valve (open / close means, exhaust merging length switching means)
88 Bracket (Cooling means)
88A Exhaust gas cooling part (gas cooling part)
88B Cooled part 96 θ pipe (divided pipe)
96A Pipe body (tube wall)
96B Partition wall 96C Open end (second opening, second junction)
98 Right bank side flow path (first exhaust pipe, one of the two exhaust paths)
100 Left bank side flow path (second exhaust pipe, one of two exhaust paths)
102 Open / close valve (open / close means, exhaust merging length switching means)
104 communication window (first opening, first junction)
112 Through hole (first opening, first merging portion, tube wall penetrating portion)
116 Valve body (one valve body)
126/128 Through hole (first opening, first junction)
142 Expansion room (space in the muffler)
192 Engine ECU (control device)
194 Exhaust temperature sensor (exhaust temperature detection means)

Claims (13)

A first opening that is communicated with an exhaust part of a first bank in the internal combustion engine and is provided at a position where a length from the exhaust part is a first predetermined length, and a length from the exhaust part is the first A first exhaust pipe having a second opening provided at a position having a second predetermined length longer than one predetermined length;
A first opening that communicates with an exhaust part of a second bank in the internal combustion engine and is provided at a position where the length from the exhaust part is a first predetermined length, and a length from the exhaust part is the first A second exhaust pipe having a second opening provided at a position having a second predetermined length longer than the predetermined length;
A first space and a second space partitioned by a separator, wherein the first exhaust pipe and the second exhaust pipe are respectively introduced; the first opening of the first exhaust pipe; The first opening of the second exhaust pipe is disposed in the first space, and the second opening of the first exhaust pipe and the second opening of the second exhaust pipe are A muffler disposed in the second space;
An opening / closing means disposed in the first space and capable of opening and closing the first opening of the first exhaust pipe and the first opening of the second exhaust pipe in synchronization with each other;
An exhaust structure for a vehicle comprising:   The opening / closing means includes: a first valve body that opens and closes the first opening of the first exhaust pipe; and a second valve body that opens and closes the first opening of the second exhaust pipe. 2. The vehicle exhaust structure according to claim 1, which is an on-off valve device configured such that the first opening of one exhaust pipe and the first opening of the second exhaust pipe are connected to open and close synchronously. Two exhaust passages communicated independently with exhaust portions of different banks of an internal combustion engine and having different exhaust merge lengths from the exhaust portions to portions where the exhaust of the two exhaust passages merge Vehicle exhaust structure that can be switched to
A first merging portion capable of merging the exhaust of the two exhaust passages at a position where the exhaust merging length is a predetermined length;
A second merging portion for merging the exhaust of the two exhaust passages at a position where the exhaust merging length is longer than that when merging at the first merging portion;
An exhaust merging length switching means for selectively switching between a state where the exhaust of the two exhaust passages merges at the first merging portion and a state where the exhaust does not merge;
Either one of the first merging portion and the second merging portion is disposed in a space formed therein, and the exhaust of the two exhaust passages in one of the first merging portion and the second merging portion. A muffler in which the two exhaust passages are introduced such that
An exhaust structure for a vehicle comprising: The muffler has another space partitioned from the space,
The vehicle exhaust structure according to claim 3, wherein the other of the first merging portion and the second merging portion is disposed in another space of the muffler.   5. The vehicle exhaust structure according to claim 4, wherein the other of the first merging portion and the second merging portion is disposed in the other space so that the gas merges through the other space of the muffler.   The two exhaust passages are configured to include a dividing pipe whose interior is partitioned by a partition wall provided along a flow direction of the exhaust gas, and the first merge portion is provided in the partition wall. The exhaust structure for a vehicle according to claim 3 or claim 4. The two exhaust passages are
Including a portion constituted by a dividing pipe whose interior is partitioned by a partition wall provided along the flow direction of the exhaust;
The end of the split pipe is the second merge part, and the pipe wall penetrating parts provided on both sides in the circumferential direction with respect to the partition wall in the pipe wall of the split pipe are the first merge part,
The vehicle exhaust structure according to any one of claims 3 to 6, wherein at least the first joining portion is disposed in a space of the muffler. The first merging portion is disposed in the space of the muffler so as to communicate with the space,
The exhaust merging length switching means switches between merging and non-merging of the exhaust of the two exhaust passages in the first merging portion, and communication and non-communication of the two exhaust passages with respect to the space in the muffler. The vehicle exhaust structure according to any one of claims 3 to 7, wherein the switching is performed by one valve body. Two exhaust passages communicated independently with exhaust portions of different banks of an internal combustion engine and having different exhaust merge lengths from the exhaust portions to portions where the exhaust of the two exhaust passages merge Vehicle exhaust structure that can be switched to
The two exhaust passages are a part constituted by a dividing pipe whose interior is partitioned by a partition wall provided along the exhaust flow direction, and a first part provided in the partition wall in the partition pipe and opened and closed by an opening / closing means. And a second merging portion disposed downstream of the first merging portion in the dividing pipe in the gas flow direction.   10. The vehicle according to claim 1, further comprising a cooling unit for lowering the temperature of the exhaust gas upstream of the first merging portion or the first opening of each of the exhaust pipes. Exhaust structure.   The cooling means spans the two exhaust passages or the first and second exhaust pipes independently communicating with different banks of the internal combustion engine, and a gas cooling section traversing the exhaust passages or the exhaust pipes. The vehicle exhaust structure according to claim 10, wherein the vehicle exhaust structure is a bracket having a portion to be cooled located outside the exhaust passage or the exhaust pipe. Engine speed detecting means for detecting the engine speed of the internal combustion engine, and exhaust gas temperature detecting means for detecting the temperature of the exhaust gas;
An actuator for operating the exhaust merging length switching means or the opening / closing means;
A control device for operating the actuator based on the detection result of the rotation speed detection means and the detection result of the exhaust gas temperature detection means;
The exhaust structure for a vehicle according to any one of claims 1 to 11, further comprising: Two exhaust passages communicated independently with exhaust portions of different banks of an internal combustion engine and having different exhaust merge lengths from the exhaust portions to portions where the exhaust of the two exhaust passages merge Vehicle exhaust structure that can be switched to
Exhaust merge length switching means for switching the exhaust merge length to a different length;
Engine speed detecting means for detecting the engine speed of the internal combustion engine, and exhaust gas temperature detecting means for detecting the temperature of the exhaust gas;
A control device that operates the exhaust merging length switching means based on the detection result of the rotational speed detection means and the detection result of the exhaust temperature detection means;
An exhaust structure for a vehicle comprising:

Images